Composition containing higher condensation products of aldehydes and aromatic amines



Patented Dec. 16 194'? COMPOSITION CONTAINING HIGHER CON- DMNSATION PRODUCTS OF ALDEHYDES AND AROMATIC AMINES John D. Bartleson, Cleveland, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application December 11, 1944, Serial No. 567,792

1 Claim. 1

This invention relates to organic compositions which are stabilized against oxidation and other forms of deterioration. More particularly, it relates to hydrocarbons, such as natural and synthetic rubbers, petroleum product-s, for example, lubricants, such as lubricating oil and grease bases, etc., which have been stabilized against deterioration under conditions of usage.

Lubricating oils, particularly when used under higher temperature conditions such as in an internal combustion engine, are subject to breakdown, oxidation, sludge formation, and the like, and tend to cause corrosion of the bearing and other metals with which they are in contact.

In order to minimize or preferably to avoid entirely serious deterioration in internal combustion engines, it is highly desirable to use lubricants which show a minimum of or are entirely free of such objectionable effects.

It is an object of the present invention to provide an agent which when added to hydrocarbons, including lubricants, will markedly inhibit the tendency thereof toward oxidative breakdown.

Another object of the invention is to provide an agent which when added to lubricating oils will markedly inhibit the corrosive effect thereof on bearing or other metal parts with which the oil comes in contact.

It is a further object of this invention to provide stabilized compositions containing such an addition agent.

Another object of the invention is to provide novel compositions which are superior in their functions to other compositions now available and intended for the same general purposes.

Other objects of this invention will become apparent as it is more fully disclosed hereinafter.

It has been proposed heretofore to react formaldehyde with primary aromatic and with monoor dialkyl aromatic amines to form diphenylmethane derivatives, known in the trade as methane bases. It has also been proposed heretofore to use the primary reaction products thereof as oxidation inhibitors. However, it has generally been considered that the secondary or higher reaction products obtained by similar processes would be detrimental when added to hydrocarbons or lubricants. Any such higher or secondary reaction products have, therefore, been separated and discarded.

It has now been found that the secondary or higher reaction products of the reaction of lower aldehydes such as formaldehyde, acetaldehyde or propionaldehyde with aromatic amines are excellent oxidation and corrosion inhibitors for hydrocarbons and in particular for lubricating oil and grease base stocks. Formaldehyde is economic and readily available so it will be used in the following disclosure; however, other lower aldehydes of not over 3 carbon atoms may be used similarly.

The secondary or higher reaction products are readily prepared by reacting the aromatic amine with the aldehyde in aqueous solution. An acid catalyst is helpful and the reaction proceeds better at an elevated temperature. The catalyst may be, for example, 6-normal hydrochloric acid. In the case of formaldehyde, 2 mols of the amine to one of the aldehyde is a preferred mol ratio.

The temperatures may be, for example, about 100 to 400 F., preferably about 200 to 212 F. The reaction rate depends on the temperature and somewhat on the amines used; it is usually completed in about 5 to 30 hours time. The resulting aqueous solution is made alkaline, steam distilled to remove any unreacted amine, and the residual water insoluble organic material separated and distilled under vacuum. Alternatively, the latter may be fractionated by recrystallization.

The primary reaction product, a diaminodiaryl-methane, comes off first in the vacuum distillation. The residue from this distillation is the secondary or higher reaction product, which is the inhibitor of the invention. It can be used in this form or can be distilled at higher temperatures and higher vacuum.

For many purposes, it is not necessary to separate the primary reaction product from the secondary or higher reaction products. For exam- I ple, the reaction mixture separated from the lower aqueous solution may be used as such. This results in an appreciable reduction in cost since the expense of vacuum distillation step is avoided.

The yields of the higher or secondary reaction products vary from about 5% to about depending upon the amine used, the reaction time and the temperature employed.

The aromatic amines used in forming these products may be primary aromatic amines such as aniline, a toluidine or a xylidine or lower N- alkyl substituted mono-cyclic aromatic amines;

alkyl-mono-cyclic aryl N-lower-alkylamines, or mixtures thereof may likewise be used. By lower alkyl is meant an alkyl group containing not over 5 carbon atoms. It is necessary that the aromatic amine be unsubstituted in the rin at either the ortho or the para position to the amino group, and have at least one hydrogen directly attached to the nitrogen since if these positions are substituted or blocked the desired reactions will not occur. These amines may be represented by the formula R1 Ra Ra I R: R4

drogen or a lower alkyl radical, and at lea-stone of the even numberedRfs is hydrogen; "1. 'ef'at' least one of R2, R4 or Re is hydrogen.

In order to point out the invention more clearly and to illustrate some of its advantages, but no wise to limit the scope of the invention as otherwise described and claimed herein, the following examples, illustrations and tests of lubri; cants comprising some of the compositions in accordance with the invention are given.

Example 1 2 mols of N-ethylaniline were mixed with 1' mol of formaldehyde (as 40% aqueous solution) and 4 mole of hydrochloric acid. This mixture was he te a 209 be F- was o rs The resulting aqueous solution was made alkaline with a u ou sodi hy rox d and s eam disti e about it me; of u reaeted N- t y ani e a ec vere thereby he res dua wate so uble or anic material wa ara ed and t en i l ed under cuum about ha of t i l ed a .61,? to 2.62? C. a ,H This di til ate. wa th primary eaction ore iuct N.N-.d e. h -abdiami enh nr m th n h re due. e produ t used in ae br ahee. with e inv nt o wa a lea is ous. amber iquid wh c a n t bearable at mom tem era ure- 2. 111015 of N-methylaniline were mixed with about 1 mol of formaldehyde (as 40% aqueous so lution) and, .4 mole of hydrochloric acid, This mixture was heated. at 200 to, .212". F. for 25L hours.

he resultin aquepl s solution was made alkaline and steam distilled; about 0.10 mol of unreacted rm thyhnifine was. ecovered t e eby. T residual wate nsoluble o an c ater al was sebarated. t wasa ixtur otthe P im rea tio produc N.N'- imeth lrb. ':dibmi o dib nyl methane an t polym r c pr du t. e.-, a x.- re. ontaining. he. pr due or an u able n ecordance with, the iny ntion. It was a. clear, visous am er. iqu d. whi h was diffie y ou bl t room m e a ure- Asi rt e llust ations. eorr soehd ne-p due rom a ol d he. a yl d he or ther am e as os d a ve may. e pr a ed; y imila P b ur s n orderteel nehstrate he. ro rt e o lu r at ng Q 9.1. .esi ie e eohteihihe h i h rma dehyde e m c amin r a hes. bredue ee orde e. "w t the invent on. a. n mbe of another paper by the same author presented at th New York city meeting or; the; American Chemical Society in September, 194%. The latter paper'al'so correlates the. results or such'laborae tory tests with the. so-called Chevrolet engine test.

Essentially the laboratory test equipment consists of a vertical, thermostatically heated, large glass test tube, into whicli'isplaced a piece of steel tubing of about one third its length and of much smaller diameter. A piece o'fcopper-lead bearing i is se h ei wi h hehe ie fi e be r a of the steeltube by a copper pin, and an air inlet is provided 'for admitting air into the lower end of the steel tube in such a way that in rising the air will cause the oil present to circulate. The a test tube is filled with an amount of the oil to be tested which is at least sufiicient to submerge the metals.

The ratios of surfaee active metals to the vol- We 01 oil an internal combustion test engine are nearly quantitatively duplicated in the test equipment. In the standard test the tempera- ;turehsed is approximately the average temperature of the crankcase, and the temperature tolerance test temperature is approximately that of the piston ring zone of a test engine in operat o T e ra of a r fle per lum o 0111s a i 'ed t a he ave a e f r a t n n i hi eh ii Cat l ti fieets .dee tb r n a e empiricallyduplicated by the addition of a soluble iron 'salt', and those duleto 'lead-bromide'by its addition'." The duration ot the test adjusted to that usually. usedin engine type tests. {is is shown by the data the papers'referred to, the laboratory tests have been correlated with engine 25 tests and'the properties of the oil in an engine may be determined from the result of the laboratory tests.

The results given herein were obtained from tests usingr A 160 cubic centimeter sample. of the. lubricant eom ositi n 0 lite s o a er. hour 99 qua e cent me e s r steel suriace 4.4 square centimeters of co pereleadi surface -0 quareeeut meters at c rn r surface 0% by wei ht. o ead bromide powder 0 solu le reh e lculated. a Ebr (ferric zr hr hex ate C, be ze The .standard tests. were. run at 280 F. for 36 1 hours. ,1 the. temperature. tolerance. (heavy duty) tests were. run at 350? F; for 10 hours. The lacquer is. deposited on the. steel tube and is determined by difierence in weight of the. tube. after washing with chloroform and drying to constant ence in weight of the copper-lead bearing strip after scrubbing. with chloroform. The used oil was fi eh to ab e the eterm nat o f. a

Tablel Pea 1 0. 0%

Lacquerfinmilligrams) 11.4 4.9 1.6 Naphtha Insolubles (in miIligrams)- 193. 3' 58.0 76; 5 Chloroform SOIllbIQS i miliisramsh. I 187.,5.. 39.6. 27.5 7 Corrosion Weight l oss Q u -lmbcaring I metal-(in milligrams); .5 7.4 4.4 l 3.8 Acidnum 28: L6 1 0i "itj illustrate: the comparative;

W h e eerr si n wasdeterm ned: by difi.

rosion characteristics, -compositions were made.

. i e f s. Wh ther bbihhs Presses e1."- ll: h:" i9h. fe b e to the corresponding primary condensation roduct, compositions similar to the foregoing were made up using 0.25% by weight of the additive and tested. The temperature tolerance test results given in Table II are representative for compositions containing an oil of the type used for the data of Table I, and the products of Example 1.

Table II Pri- Higher Blank mary Boiling Lacquer (in mil igrams) 4. 8 8.5 4. 5 Naphtha Insolubles (in milligrams) 235.1 277.1 174. 7 Chloroform Solubles (in milligrams). 229.3 194. 7 87. 7

Corrosion Wei ht Loss Cu-Pb bea g metal (in milligram) 25. 2 10. 9 0. 7 Acid number. 2. 2 1. 6 1. 2 Viscosity Increase (S. U. S.) 1479 453 214 To illustrate the value of the products of the Table III (a) With Addi- Blank five Corrosion Weight Loss Cu-Pb bearing metal (in milligrams) l0. 4 2.7 Acid number 2. 5 1.0 Viscosity Increase (S. U. S 391 114 Table III (1)) With Addi- Blank five Corrosion Weight Loss Cu-Pb bearing metal These tests show the marked improvement imparted to the lubricating oils by the higher boiling condensation products in accordance with the invention and the superiority of these higher products over the primary products as additives. They also show that mixtures of the primary and higher reaction products may be used to advantage.

It will be obvious to one skilled in the art that products obtained by different procedures but having substantially the same chemical and physical properties as those herein described may be used in accordance with the invention. The invention as claimed contemplates all such compositions within the scope of the appended claim.

The term lubricant appearing in the appended claims is intended to mean the ordinarily used base stock lubricating oils, greases, and the like.

I claim:

A lubricating composition adapted for use in lubricating internal combustion engines containing copper-lead bearings, which composition comprises a major proportion of the lubricating oil normally deteriorative under conditions of service so as to be corrosive with copper-lead bearings, and a minor amount of an additive suflicient to stabilize said oil and markedly inhibit the corrosive properties of said oil, said additive being the condensation product of the reaction of about 1 mol of formaldehyde with about 2 mols of N-ethyl aniline reacted in an aqueous acidic solution at an elevated temperature, and boiling above and separated from any condensation product boiling lower than 262 C. at 9 mm. Hg absolute pressure.

JOHN D. BARTLESON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,556,415 Caldwell Oct. 6, 1925 1,594,983 Sommerville Aug. 3, 1926 1,939,192 Williams Dec. 12, 1933 2,113,599 Musselman Apr. 12, 1938 1,890,917 Semon Dec. 13, 1932 2,223,411 Fuller Dec. 3, 1940 2,395,093 Bishop Feb. 19, 1946 

